Packages and modules having components with large ground connections are difficult to solder due to a build up of hot gasses that cannot escape between the components and a mounting surface. The hot gasses create voids in the solder when the package cools after reflow. The voids cause heating problems for high power components at all frequencies. For packages and modules at higher frequencies, a detrimental impact on radio frequency grounding is experienced.
A conventional solution is to break the large ground area connections into isolated subsections thereby creating gaps between the areas of ground metal through which the hot gasses can escape. At low frequencies the gaps provide an acceptable degradation of the ground plane. At middle frequencies, the gap approach starts to fail as the extra discontinuities in the ground plane matter. At high frequencies, multilayer packages with various gaps start to deteriorate as the parasitics of vertical trace transitions through the multilayer package start to become important.
It would be desirable to implement a ground pattern for solderability and radio-frequency properties in millimeter-wave packages.